/usr/lib/ruby/1.9.1/psych/ is in libruby1.9.1 1.9.3.0-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/1.9.1/psych/coder.rb
/usr/lib/ruby/1.9.1/psych/core_ext.rb
/usr/lib/ruby/1.9.1/psych/deprecated.rb
/usr/lib/ruby/1.9.1/psych/handler.rb
/usr/lib/ruby/1.9.1/psych/json/
/usr/lib/ruby/1.9.1/psych/json.rb
/usr/lib/ruby/1.9.1/psych/json/ruby_events.rb
/usr/lib/ruby/1.9.1/psych/json/stream.rb
/usr/lib/ruby/1.9.1/psych/json/tree_builder.rb
/usr/lib/ruby/1.9.1/psych/json/yaml_events.rb
/usr/lib/ruby/1.9.1/psych/nodes/
/usr/lib/ruby/1.9.1/psych/nodes.rb
/usr/lib/ruby/1.9.1/psych/nodes/alias.rb
/usr/lib/ruby/1.9.1/psych/nodes/document.rb
/usr/lib/ruby/1.9.1/psych/nodes/mapping.rb
/usr/lib/ruby/1.9.1/psych/nodes/node.rb
/usr/lib/ruby/1.9.1/psych/nodes/scalar.rb
/usr/lib/ruby/1.9.1/psych/nodes/sequence.rb
/usr/lib/ruby/1.9.1/psych/nodes/stream.rb
/usr/lib/ruby/1.9.1/psych/omap.rb
/usr/lib/ruby/1.9.1/psych/parser.rb
/usr/lib/ruby/1.9.1/psych/scalar_scanner.rb
/usr/lib/ruby/1.9.1/psych/set.rb
/usr/lib/ruby/1.9.1/psych/stream.rb
/usr/lib/ruby/1.9.1/psych/streaming.rb
/usr/lib/ruby/1.9.1/psych/tree_builder.rb
/usr/lib/ruby/1.9.1/psych/visitors/
/usr/lib/ruby/1.9.1/psych/visitors.rb
/usr/lib/ruby/1.9.1/psych/visitors/depth_first.rb
/usr/lib/ruby/1.9.1/psych/visitors/emitter.rb
/usr/lib/ruby/1.9.1/psych/visitors/json_tree.rb
/usr/lib/ruby/1.9.1/psych/visitors/to_ruby.rb
/usr/lib/ruby/1.9.1/psych/visitors/visitor.rb
/usr/lib/ruby/1.9.1/psych/visitors/yaml_tree.rb